This application claims the priority of German Patent Application 100 36 337.7, filed 26 Jul. 2000 (PCT International Application No. PCT/EP01/08393, filed 20 Jul. 2001), the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and apparatus for setting a desired deceleration of a vehicle when the accelerator pedal and the brake pedal are not operated.
In vehicles, particularly passenger cars and trucks, the accelerator pedal and the brake pedal are used for accelerating the vehicle and holding the driving speed, and for decelerating the vehicle, respectively. In certain traffic situations, the driver is forced to change constantly between operating the accelerator pedal and operating the brake pedal, particularly in lines of traffic, such as on turnpikes where a so-called accordion effect may occur. It is uncomfortable and tiring for the driver to be required constantly to move the right foot between the accelerator pedal and the brake pedal; drivers of automatic-transmission vehicles may therefore be tempted to “drive with both feet”. That is, the right foot is placed on the accelerator pedal while the left foot is on the brake pedal, which may lead to a constant operation of the brake and a resulting increased wearing of the brake, as well as an increased gasoline consumption because the engine and the brake continuously counteract one another.
It is an object of the present invention to provide a method and apparatus which improve comfort and the safety when driving a vehicle.
This and other objects and advantages are achieved by the invention, in which the driving speed of a vehicle is controlled by operating or releasing the accelerator. A desired deceleration can be set by means of an operating device, and the vehicle is braked by the desired deceleration when the accelerator pedal is released. This adjustable desired deceleration is preferably greater than the inherent deceleration which otherwise occurs when the accelerator is released so that the engine does not supply any driving power. This applies to vehicles with a manual transmission as well as to vehicles with an automatic transmission, which have only a low drag momentum when the accelerator is released (that is, a low inherent deceleration).
The invention can be used in combination with existing braking systems, and also in combination with devices for controlling the driving speed, such as cruise controls and the ACC. In particular, the invention can be used in combination with power braking systems which can build up wheel-individual brake pressure, independently of the control by the driver, at all wheels, for example, the DSC. The invention can also be used in braking systems with automatic brake intervention by means of a hydraulic unit or a controllable brake power assist unit, as, for example, in the ACC operation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.